`run-task` image does not put required deps in the path

Start by tracing how the run-task image installs requirements.in into requirements.txt and configures the runtime environment. Reproduce the logged install and taskgraph decision command, then verify that the taskgraph executable is available during execution. Done means the example command runs successfully without “taskgraph: command not found”.

I have taskcluster-taskgraph in my requirements.in file and would expect the binary to be in my path during runtime.

Example task https://community-tc.services.mozilla.com/tasks/f3hPgRYPSSeU6HJQGdM19Q/runs/0/logs/live/public/logs/live.log#L80-136

pip install and task execution logs:

[pip-install 2025-10-14T21:17:33.179+00:00] executing ['uv', 'pip', 'install', '--python', '/usr/bin/python3', '--target', '/builds/worker/.local/lib/python3.11/site-packages', '--require-hashes', '-r', '/builds/worker/checkouts/src/taskcluster/requirements.txt']
[pip-install 2025-10-14T21:17:33.222+00:00] Using CPython 3.11.2 interpreter at: /usr/bin/python3
[pip-install 2025-10-14T21:17:33.520+00:00] Resolved 44 packages in 295ms
[pip-install 2025-10-14T21:17:33.573+00:00] Downloading aiohttp (1.7MiB)
[pip-install 2025-10-14T21:17:33.575+00:00] Downloading pygments (1.2MiB)
[pip-install 2025-10-14T21:17:33.740+00:00]  Downloaded aiohttp
[pip-install 2025-10-14T21:17:33.785+00:00]  Downloaded pygments
[pip-install 2025-10-14T21:17:33.785+00:00] Prepared 44 packages in 263ms
[pip-install 2025-10-14T21:17:33.807+00:00] Installed 44 packages in 21ms
[pip-install 2025-10-14T21:17:33.807+00:00]  + aiohappyeyeballs==2.6.1
[pip-install 2025-10-14T21:17:33.807+00:00]  + aiohttp==3.13.0
[pip-install 2025-10-14T21:17:33.807+00:00]  + aiosignal==1.4.0
[pip-install 2025-10-14T21:17:33.807+00:00]  + appdirs==1.4.4
[pip-install 2025-10-14T21:17:33.807+00:00]  + arrow==1.3.0
[pip-install 2025-10-14T21:17:33.807+00:00]  + async-timeout==5.0.1
[pip-install 2025-10-14T21:17:33.807+00:00]  + attrs==25.4.0
[pip-install 2025-10-14T21:17:33.807+00:00]  + binaryornot==0.4.4
[pip-install 2025-10-14T21:17:33.807+00:00]  + certifi==2025.10.5
[pip-install 2025-10-14T21:17:33.807+00:00]  + chardet==5.2.0
[pip-install 2025-10-14T21:17:33.807+00:00]  + charset-normalizer==3.4.4
[pip-install 2025-10-14T21:17:33.807+00:00]  + click==8.3.0
[pip-install 2025-10-14T21:17:33.807+00:00]  + cookiecutter==2.6.0
[pip-install 2025-10-14T21:17:33.807+00:00]  + frozenlist==1.8.0
[pip-install 2025-10-14T21:17:33.807+00:00]  + giturlparse==0.12.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + idna==3.11
[pip-install 2025-10-14T21:17:33.808+00:00]  + jinja2==3.1.6
[pip-install 2025-10-14T21:17:33.808+00:00]  + json-e==4.8.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + markdown-it-py==4.0.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + markupsafe==3.0.3
[pip-install 2025-10-14T21:17:33.808+00:00]  + mdurl==0.1.2
[pip-install 2025-10-14T21:17:33.808+00:00]  + mohawk==1.1.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + mozilla-repo-urls==0.2.2
[pip-install 2025-10-14T21:17:33.808+00:00]  + multidict==6.7.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + propcache==0.4.1
[pip-install 2025-10-14T21:17:33.808+00:00]  + pygments==2.19.2
[pip-install 2025-10-14T21:17:33.808+00:00]  + python-dateutil==2.9.0.post0
[pip-install 2025-10-14T21:17:33.808+00:00]  + python-slugify==8.0.4
[pip-install 2025-10-14T21:17:33.808+00:00]  + pyyaml==6.0.3
[pip-install 2025-10-14T21:17:33.808+00:00]  + redo==3.0.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + requests==2.32.5
[pip-install 2025-10-14T21:17:33.808+00:00]  + rich==14.2.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + six==1.17.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + slugid==2.0.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + taskcluster==91.0.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + taskcluster-taskgraph==16.2.1
[pip-install 2025-10-14T21:17:33.808+00:00]  + taskcluster-urls==13.0.1
[pip-install 2025-10-14T21:17:33.808+00:00]  + text-unidecode==1.3
[pip-install 2025-10-14T21:17:33.808+00:00]  + toml==0.10.2
[pip-install 2025-10-14T21:17:33.808+00:00]  + types-python-dateutil==2.9.0.20251008
[pip-install 2025-10-14T21:17:33.808+00:00]  + typing-extensions==4.15.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + urllib3==2.5.0
[pip-install 2025-10-14T21:17:33.808+00:00]  + voluptuous==0.15.2
[pip-install 2025-10-14T21:17:33.808+00:00]  + yarl==1.22.0
[task 2025-10-14T21:17:33.815+00:00] executing ['bash', '-cx', 'ln -s /builds/worker/artifacts artifacts && taskgraph decision --pushlog-id=\'0\' --pushdate=\'0\' --project=\'taskcluster\' --message="" --owner=\'taskcluster-internal@mozilla.com\' --level=\'1\' --repository-type=git --target-tasks-method=taskcluster-branches --tasks-for=\'github-pull-request\' --base-repository=\'https://github.com/taskcluster/taskcluster\' --base-ref=\'main\' --base-rev=\'0fe066c9a95e48b26b582824b00d97d0b0f96181\' --head-repository=\'https://github.com/taskcluster/taskcluster\' --head-ref=\'matt-boris/taskgraph16.2.1\' --head-rev=\'afe5a53d14b89c6946551761187c74c4b14d5bd2\' --head-tag=\'\' && echo "{}" > artifacts/actions.json # taskcluster is not using actions.json, setting to {} so CoT can still verify\n']
[task 2025-10-14T21:17:33.816+00:00] + ln -s /builds/worker/artifacts artifacts
[task 2025-10-14T21:17:33.817+00:00] + taskgraph decision --pushlog-id=0 --pushdate=0 --project=taskcluster --message= --owner=taskcluster-internal@mozilla.com --level=1 --repository-type=git --target-tasks-method=taskcluster-branches --tasks-for=github-pull-request --base-repository=https://github.com/taskcluster/taskcluster --base-ref=main --base-rev=0fe066c9a95e48b26b582824b00d97d0b0f96181 --head-repository=https://github.com/taskcluster/taskcluster --head-ref=matt-boris/taskgraph16.2.1 --head-rev=afe5a53d14b89c6946551761187c74c4b14d5bd2 --head-tag=
[task 2025-10-14T21:17:33.818+00:00] bash: line 1: taskgraph: command not found